Toroidal continuously variable transmissions are already generally known, as is disclosed for example in Japanese Patent Application Laid-Open No. 2000-257685. A toroidal continuously variable transmission is constructed from an input disk that is rotationally driven by an engine or the like, an output disk that is disposed facing this input disk so that relative rotation is possible, a trunnion assembly which is clamped between the input and output disks, and which performs a swinging motion, and a pushing mechanism (loading mechanism) which pushes the input disk and output disk in the directions that clamp the trunnion assembly. Such a transmission is constructed so that the speed reduction ratio between the input and output disks can be controlled in a continuously variable manner by swinging the trunnion assembly. In this case, the pushing mechanism is constructed so that (for example) the input disk is pushed toward the output disk by hydraulic pressure, and this pushing force is set in accordance with the input torque or the like. As a result, the clamping force of the trunnion assembly between the input and output disks is appropriately set in accordance with the input torque, and slipping between the input and output disks and the trunnion assembly is prevented so that power transmission is accomplished with high efficiency.
Since the apparatus is thus constructed so that the input and output disks clamping the trunnion assembly are pushed in the axial direction by a pushing mechanism, the input and output disks are moved in the axial direction while undergoing elastic deformation in accordance with the pushing force. In order to allow such movement in the axial direction, the drive shaft that is driven by the engine and the input shaft to which the input disk is attached are constructed as separate parts, and a rotary connecting mechanism is provided which transmits rotation while allowing movement of the input shaft in the axial direction relative to the drive shaft. For example, such a rotating connecting structure may have a construction in which disk-form parts that face each other are respectively disposed on the drive shaft and the input shaft, first and second engaging parts are constructed by forming a plurality of teeth that protrude toward each other in the axial direction on the outer circumferences of these disk-form parts, and engaging the teeth of these first and second engaging parts, as disclosed in the abovementioned patent.
However, in cases where the drive shaft and input shaft are constructed as separate parts as described above, the following problem arises: specifically, if any axial deviation occurs in the shafts, or if biased load acts on the shafts, a biased load will be applied to the tooth surfaces of the engaging parts, so that relative movement between the two shafts in the axial direction is impeded, and so that the tooth surfaces are damage. One conceivable method of alleviating this problem of axial deviation and biased loads is to increase the precision of the parts; however, this leads to the problem of increased manufacturing costs. Furthermore, axial deviation and biased loads can also be suppressed by increasing the installation span of the bearings that support the shafts so that the shafts are free to rotate; however, this leads to the problem of an increase in the axial dimension of the apparatus and an increase in the size of the transmission.